Vivotif: Live, attenuated oral typhoid vaccine, Vivotif, contains 2-6x109 CFU (colony-forming units) of S. Typhi Ty21a strain (1,2). The Berna Biotech Ltd, Berne, Switzerland, manufactures this vaccine. The enteric-coated, typhoid vaccines are packaged as sets of 3-capsules. The vaccine capsule is swallowed with drinking water and administered on alternate days i.e. days 1, 3 and 5. For immunization of children under 5 years of age, we plan to administer the vaccine in bicarbonate buffer as is the procedure in for children in travelers clinics (Sweden and USA). For this purpose the capsule is opened up and the contents suspended in 20 ml of bicarbonate buffer and then taken orally.